The present invention relates to an unstacker and method for unstacking items being conveyed in a bulk stream.
The handing of items such as cartons, parcels, bundles, magazines, polybags, etc. often involves conveying the items in a bulk stream while stacked one upon the other. In order for the items to be properly handled, e.g., to redirect magazines to their intended destination, it may be necessary to first destack the items.
Various ways of unstacking items have been proposed, e.g., see the disclosures of U.S. Pat. Nos. 2,006,870; 4,150,743; 5,069,440; and 5,201,397. U.S. Pat. No. 2,006,870 describes a decline unstacker for unstacking bundles of sugar being conveyed in stacks along a horizontal flight of an endless conveyor. The horizontal flight transforms into a declined flight, causing the top items to slide off the bottom items and onto a declined chute. At the bottom of the chute a rapidly moving horizontal endless conveyor pulls the items successively away. Among the problems occurring in connection with such a decline unstacker is that the bottom bundles may form a continuous line of bundles along the declined flight of the feed conveyor and the chute, whereby the top bundles simply slide upon that line of bundles without ever becoming unstacked.
It is, therefore, an object of the invention to provide an unstacker and method which minimizes or obviates those and other problems.
The present invention relates to a decline unstacking apparatus and an incline unstacking apparatus which can be combined in series, or utilized separately.
The decline unstacking apparatus comprises a feed conveyor for feeding stacks of items, and a declined conveyor arrangement including at least first and second declined conveyors arranged in series. A first of the declined conveyors has an upstream end disposed at a discharge end of the feed conveyor. The first declined conveyor is declined at an angle relative to a direction of travel of the feed conveyor whereby items in a stack being discharged from the feed conveyor tilts to cause the items in the stack to slide off one another into a shingle arrangement on the first declined conveyor. The second declined conveyor includes an upstream end disposed adjacent a downstream end of the first declined conveyor and traveling at a faster speed than the first declined conveyor, whereby the second declined conveyor tends to separate the items received from the first declined conveyor.
Preferably, a sensor is provided for sensing items on the first declined conveyor. A controller is provided for controlling a speed of the feed conveyor in response to signals from the sensor, for preventing a discharge of additional items onto the first declined conveyor until there is space on the first declined conveyor for receiving additional items.
An upstream end of a conveying surface defined by the second declined conveyor is preferably offset upwardly with respect to a path of travel of the downstream end of a conveying surface defined by the first declined conveyor, causing a leading end of each item to be raised when passing from the first declined conveyor to the second declined conveyor.
Another aspect of the invention relates to a method of unstacking items fed in stacked relationship in a bulk stream. The method comprises the steps of:
A) feeding the stream along a feed conveyor to an upstream end of a declined conveyor arrangement which comprises at least first and second declined conveyors arranged in series, whereby a stack of items tilts as it reaches an upstream end of the first declined conveyor, causing the items to slide off one another into a shingle arrangement on the first declined conveyor; and
B) driving the second declined conveyor at a faster speed than the first declined conveyor whereby the second declined conveyor tends to separate the items received from the first declined conveyor.
Preferably, the method includes the steps of sensing items on the first declined conveyor, and regulating a speed of the feed conveyor in response to signals from the sensor, to prevent the discharge of additional items to the first declined conveyor until there is space on the first declined conveyor for receiving additional items.
The incline unstacking apparatus comprises a feed conveyor for feeding stacks of items, and an inclined conveyor arrangement including at least first and second inclined conveyors arranged in series. A first of the inclined conveyors has an upstream end disposed at a discharge end of the feed conveyor. The first inclined conveyor is inclined at an angle relative to a direction of travel of the feed conveyor whereby items in a stack being discharged from the feed conveyor tilts rearwardly to cause the items in the stack to slide rearwardly off one another into a shingle arrangement on the first inclined conveyor. The second inclined conveyor includes an upstream end disposed adjacent a downstream end of the first inclined conveyor and traveling at a faster speed than the first inclined conveyor, whereby the second inclined conveyor tends to separate the items received from the first inclined conveyor.
Preferably, a sensor is provided for sensing items on the first inclined conveyor. A controller is provided for controlling a speed of the feed conveyor in response to signals from the sensor, for preventing a discharge of additional items onto the first inclined conveyor until there is space on the first inclined conveyor for receiving additional items.
An upstream end of a conveying surface defined by the second inclined conveyor is preferably offset downwardly with respect to a path of travel of the downstream end of a conveying surface defined by the first inclined conveyor, causing a leading end of each item to descend when passing from the first inclined conveyor to the second inclined conveyor.
Another aspect of the invention relates to a method of unstacking items fed in stacked relationship in a bulk stream. The method comprises the steps of:
A) feeding the stream along a feed conveyor to an upstream end of an inclined conveyor arrangement which comprises at least first and second inclined conveyors arranged in series, whereby a stack of items tilts rearwardly as it reaches an upstream end of the first inclined conveyor, causing the items to slide rearwardly off one another into a shingle arrangement on the first inclined conveyor; and
B) driving the second inclined conveyor at a faster speed than the first inclined conveyor whereby the second inclined conveyor tends to separate the items received from the first inclined conveyor.
Preferably, the method includes the steps of sensing items on the first inclined conveyor, and regulating a speed of the feed conveyor in response to signals from the sensor, to prevent the discharge of additional items to the first inclined conveyor until there is space on the first inclined conveyor for receiving additional items.